Password encryption is a paramount requirement to control access to web applications and protect confidential information. A password in clear text is vulnerable to interception and eavesdropping on the Internet, which may result in significant information and financial loss to its owner. Public key encryption algorithms that are in use today provide computationally unbreakable encryption to passwords, as discussed in “A Web-only Primer on Public-key Encryption”, http://www.theatlantic.com/doc/200209/mann_g. Though these algorithms are perceived to be unbreakable with today's possible computational speeds, there lies no guarantee that the same situation will continue in future, taken into consideration various factors such as the level of currently ongoing academic research to break these algorithms, continuously increasing processing power of computers, and the application of parallel processing techniques and quantum computers to factorize large numbers (see “Public-Key Cryptography”, http://cam.qubit.org/articles/crypto/publickey.php, and Nielsen, Michael A. and Chuang, Isaac L., “Quantum Computation and Quantum Information”, Cambridge University Press, Cambridge, 2000).
None of the proven public key cryptosystems as of today provide absolute security, that is, never-breakable security. The most well known and widely implemented public key cryptosystem for information security is the RSA algorithm, whose security lies in the difficulty of factoring the key modulus into its primes (see “Modular Mathematics”, RSA cryptography, http://www.mathreference.com/nummod.rsa.html). “RSA” stands for the surnames of Ron Rivest, Adi Shamir, and Leonard Adelman, who publicly described the RSA algorithm or method in 1977. If someone invents in the future a trivial factoring technique for large numbers, it will mark the end of the RSA cryptosystem, resulting in a drastic impact on e-commerce and e-banking activities.
Further, public key cryptosystems are vulnerable to spoofing attacks (see “The Pure Crypto Project”, Remarks on Security, http://senderek.com/pcp/pcp-security.html), which can be easily crafted by a man-in-the-middle. A spoofed public key can render an otherwise secure communication insecure (see “Easy Fast Efficient Certification Technique”, http://pdos.csail.mit.edu/asrg/2000-10-30.ppt). These attacks are not computationally intensive in nature unlike factoring attacks. Spoofing attacks can be mounted in real time without requiring any sophisticated computing infrastructure. Though web browsers verify the authenticity of public keys and provide alerts to users on mismatching keys, most users are unaware of the subject matter and technically not sound enough to understand the seriousness of the problem and be vigilant to notice spoofing attacks.
Research was done in the past to devise public key cryptographic techniques that survive private key compromise attacks (see Cheman Shaik, “Robust Public Key Cryptography—a New Crypto System Surviving Private Key Compromise. Proceedings of the Second European Conference on Computer Network Defense). However, more research needs to be done in the direction of developing new password encryption techniques that withstand factoring and key spoofing attacks.